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Identifying Douglas Engine

Started by Michel H, 08 Jun 2013 at 16:45

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Michel H

Hello, last week I bought what I believed to be an EW350cc incomplete engine (only for the spare parts). The sale included the two crankcases timing and flywheel sections, the two complete cylinders with valves. No crankshaft  or piston. The bore is right 60,80 mm. Of course I cannot measure the stroke but the piston's marks are +/- 60 mm and the deep of cylinders is +/_ 120 mm. Both parts of crankcase are stamped A50. The operating cam is stamped 7113-1 (in the spare parts list the right number is 7113). No other number on the cylinders or somewhere else. I don't found the reference A50 in "The Best Twin" from J.R. Clew. It's possible it Should be a stationary engine ? Does some one have an idea ? Thanks.
Michel

Doug

Michel,

A50 are just the crankcase match-marks, indicating the two halves were machined together. 7113 verse 7113-1 on the clutch operating arm indicates a newer revision of the same base part 7113, and interchangeable. (If it were not interchangeable, it would have been given a new part number.)

The engine serial number should be on the top surface of the crankcase, adjacent to where the magneto clamps.

-Doug

Michel H

Good evening Doug,
Where the engine number schoud be, there one hole with both sides two little holes for fixing screw.
I think there were a pipe.
Strange, isn'it ?
Michel.
Michel

Doug

Michel,

That sounds like the attachment point for the breather, but that style was used on the 1930s 350cc crankcases. And the breather was off the top surface to the rear of the magneto. If the breather is on the front edge, perhaps someone added it and obliterated the serial number.

Is the bottom edge of the timing chest curved (EW) or straight (B29 and later)?

-Doug

Michel H

Good evening Doog,
The bottom edge of the timing chest is traight. So it's B29 and later.
I don't buy it for the crankcase but for (important to me) the cylinders, the valves and their springs and (secondary important) the pushrods and the timing gears.
Do you think that the cylinders ore any others parts are right for EW350 ?
Have a nice week-end.
Michel.
Michel

Doug

Michel,

Well it depends...

...on how much later it is. A B29 has detachable cylinder heads, as did the Sports version of the EW. There are subtle differences to the castings, but nothing that would stop you from installing - I think - them onto an EW. That would hold true through the L3/H3 models, the A31/A32 models, and the Y1 model of 1934. In 1935, the 350cc dropped the gland nuts for the ports and adopted the flanged ports seen on the 250cc model of 1934. I am pretty sure you can still swap over the entire cylinder assembly of the 350cc Aero models on the EW crankcase, but obviously you would have to replace your intake manifold and exhaust system too.

Later tappet guides have a conical seat, they do not thread in like the EW. Not sure when the change over was. But the tappets and lash adjusters should be identical right to the end. Ditto valves and valve springs, but these are available new to LDMCC members. The timing gears and cams are generally the same, but they did make changes to the end of the end of the one cam wheel to provide a drive dog to the oil pump worm (the EW oil pump worm is integral with the crankshaft pinion nut.)

-Doug

Michel H

Good morning Doug,
The cylinders are no detachable cylinders heads. The intake manifold and the exhaust system have the right screw pitch.
As much as I can see the cylinders and the tappets seem to be the right one. For me it's the most important.
I thank you very much for all your explanations.
Regard. Michel.
Michel